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Abstract:

A method for detecting hidden explosives or weapons, including
transmitting a signal in different polarization channels towards an
object, the next stage includes collecting back scattered energy in
different polarization channels from the object, the next stage includes
determining parameters that are dependent upon the transmitted signal
polarization channels and the backscattered energy polarization channels,
and providing an indication if there are hidden explosives or weapons in
the object based on the parameters.

Claims:

1. A method for detecting hidden explosives or weapons, comprising (a)
transmitting a signal in different polarization channels towards an
object; (b) collecting back scattered energy in different polarization
channels from the object; (c) determining parameters that are dependent
upon at least the transmitted signal polarization channels and the
backscattered energy polarization channels, providing an indication if
there are hidden explosives or weapons in the object based on said
parameters.

2. The method according to claim 1, wherein said different polarization
channels being horizontal polarization and vertical polarization.

3. The method according to anyone of the preceding claims wherein said
object being a human.

4. The method according to anyone of claims 1 to 4, wherein said object
being bushes and wherein said explosives or weapons are concealed in the
bushes.

5. The method according to anyone of the preceding claims, wherein said
determination of parameters stipulated in (c) includes i) evaluating full
polarization scattering matrices of range Doppler cells that belong to
the object; ii) calculating correlation between elements of the
polarization scattering matrices giving rise to a covariance matrix; iii)
analyzing polarimatric results for the covariance matrix; the
polarimetric results include at least eigenvalues and corresponding
eigenvectors, and iv) utilizing said eigenvalues and eigenvectors to
determine whether to generate an indication that there are hidden
explosives or weapons in the object.

6. The method according to anyone of claims 2 to 5, wherein said
transmitting being in circular polarization.

7. The method according to anyone of the preceding claims, further
comprising acquiring images of said object.

8. The method according to anyone of the preceding claims configured to
be used on mobile platform for detecting hidden explosives or weapons in
a stationary object.

9. The method according to anyone of the claims 1 to 7, configured to be
used on a stationary platform for detecting hidden explosives or weapons
in a stationary object.

10. The method according to anyone of claim 8 or 9, wherein said object
being bushes.

11. The method according to anyone of claims 8 to 10, wherein said
explosives or weapons include hidden missiles or launchers.

12. The method according to anyone of the claims 1 to 7, configured to be
used on mobile platform for detecting hidden explosives or weapons in a
moving object.

13. The method according to anyone of the claims 1 to 7, configured to be
used on a stationary platform for detecting hidden explosives or weapons
in a moving object.

14. A system for detecting hidden explosives or weapons, comprising
transmitter configured to transmit a signal in different polarization
channels towards an object; receiver configured to receive back scattered
energy in different polarization channels from the object; a processor
configured to determine parameters that are dependent upon at least the
transmitted signal polarization channels and the backscattered energy
polarization channels, providing an indication if there are hidden
explosives or weapons in the object based on said parameters.

15. The system according to claim 14, wherein the transmitter being a
radar system configured to transmit a Frequency Modulated Continuous Wave
(FMCW) or pulsed or CW signal.

16. A system for detecting hidden explosives or weapons, comprising a a
polarimetric transmitter/receiver module which is configured to switch
between horizontal and vertical polarized signal transmissions utilizing
a transmitter antenna; a receiver configured to receive a back scattered
signal and split the received signal into vertical (V) and horizontal (H)
components; A2D configured to receive said vertical (V) and horizontal
(H) components through V and H channels and converting the backscattered
signals into digital signals; a processor configured to process the
digitized signals for determining whether the object conceals explosives
or weapons.

17. The system according to claim 16, wherein said module being a
Frequency Modulated Continuous Wave (FMCW) or pulsed or CW module.

Description:

FIELD OF THE INVENTION

[0001] This invention relates to a system and method for detecting
concealed explosives and weapons.

BACKGROUND OF THE INVENTION

[0002] Terrorist activities have become a growing problem all over the
world. These include suicide bombers carrying explosives, armed
terrorists carrying various concealed weapons, and also missiles and
launchers of different sizes hidden between bushes or other kind of
vegetation.

RELATED ART

[0003] U.S. Pat. No. 6,967,612 discloses "a system and method for standoff
detection of human carried explosives (HCE) is a portable system that
automatically detects HCE up to a range of 200 meters and within seconds
alerts an operator to HCE threats. The system has radar only, or both
radar and video sensors, a multi-sensor processor, an operator console,
handheld displays, and a wideband wireless communications link. The
processor receives radar and video feeds and automatically tracks and
detects all humans in a field of view. Track data continuously cues the
narrow beam radar to a subject of interest, the radar repeatedly
interrogating cued objects, producing a multi-polarity radar range
profile for each interrogation event. Range profiles and associated
features are automatically fused over time until sufficient evidence is
accrued to support a threat/non-threat declaration hypothesis. Once a
determination is made, the system alerts operators through a handheld
display and mitigates the threat if desired."

[0004] There is a need in the art for detecting hostiles carrying
explosives or weapons at a safe distance and provide appropriate alert in
good time before the explosive and/or the weapons are activated against
friendly targets, such as innocent civilians.

[0005] There is further need in the art for detecting a threat such as
hidden missiles or launchers (e.g. concealed between bushes) and
distinguishing between them and rocks, trees or other harmless detected
objects, facilitating thus destruction or dismantling of the threat.

SUMMARY OF THE INVENTION

[0006] In accordance with certain embodiments, fully polarized coherent
Frequency Modulation Continuous Wave (FMCW) radar is used to detect and
track targets of interest. The usage of coherent FMCW radar facilitates
generation of Range-Doppler maps in which the targets are detected and
tracked down. The frequency of each pulse is linearly increasing and the
total span covered is termed bandwidth. As is well known the FMCW enables
to separate targets at different ranges where the range resolution is
inversely proportional to the bandwidth. Consecutive pulses are then
processed to obtain the Doppler frequency (proportional to target
velocity projection on the radar line of sight). The Doppler resolution
is inversely proportional to the integration time (i.e. number of pulses
processed).

[0007] Reverting to the Range-Doppler maps, for each target detection
along a track, correlations between different polarizations scattering
matrix elements are analyzed. The nature of these correlations is shown
to have features that enable identification of presence of explosives or
concealed weapons and other targets of interest.

[0008] In accordance with certain embodiments, there is provided a system
that includes a fully polarized coherent FMCW radar, an A2D and DSP card
in a PC and a video camera used for monitoring purposes only. The system
processes the data to obtain Range Doppler maps, performs target
detection and calculates polarimetric features of the target in real
time. The data is analyzed, and an alarm flag is turned on based on the
results of the analysis.

[0009] Accordingly, there is provided a method for detecting hidden
explosives or weapons, comprising [0010] (a) transmitting a signal in
different polarization channels towards an object; [0011] (b) collecting
back scattered energy in different polarization channels from the object;
[0012] (c) determining parameters that are dependent upon at least the
transmitted signal polarization channels and the backscattered energy
polarization channels, providing an indication if there are hidden
explosives or weapons in the object based on said parameters.

[0013] In accordance with certain embodiments, there is provided a method
wherein said different polarization channels being horizontal
polarization and vertical polarization.

[0014] In accordance with certain embodiments, there is provided a method
wherein said object being a human.

[0015] In accordance with certain embodiments, there is provided a method
wherein said object being bushes and wherein said explosives or weapons
are concealed in the bushes.

[0016] In accordance with certain embodiments, there is provided a method
wherein said determination of parameters stipulated in (c) includes
[0017] i) evaluating full polarization scattering matrices of range
Doppler cells that belong to the object; [0018] ii) calculating
correlation between elements of the polarization scattering matrices
giving rise to a covariance matrix; [0019] iii) analyzing polarimatric
results for the covariance matrix; the polarimetric results include at
least eigenvalues and corresponding eigenvectors, and [0020] iv)
utilizing said eigenvalues and eigenvectors to determine whether to
generate an indication that there are hidden explosives or weapons in the
object.

[0021] In accordance with certain embodiments, there is provided a method
wherein said transmitting being in circular polarization.

[0022] In accordance with certain embodiments, there is provided a method
further comprising acquiring images of said object.

[0023] In accordance with certain embodiments, there is provided a method
configured to be used on mobile platform for detecting hidden explosives
or weapons in a stationary object.

[0024] In accordance with certain embodiments, there is provided a method
configured to be used on a stationary platform for detecting hidden
explosives or weapons in a stationary object.

[0025] In accordance with certain embodiments, there is provided a method
wherein said object being bushes.

[0026] In accordance with certain embodiments, there is provided a method
wherein said explosives or weapons include hidden missiles or launchers.

[0027] In accordance with certain embodiments, there is provided a method
configured to be used on mobile platform for detecting hidden explosives
or weapons in a moving object.

[0028] In accordance with certain embodiments, there is provided a method
configured to be used on a stationary platform for detecting hidden
explosives or weapons in a moving object.

[0029] In accordance with an aspect of the invention, there is provided a
system for detecting hidden explosives or weapons, comprising [0030]
transmitter configured to transmit a signal in different polarization
channels towards an object; [0031] receiver configured to receive back
scattered energy in different polarization channels from the object;
[0032] a processor configured to determine parameters that are dependent
upon at least the transmitted signal polarization channels and the
backscattered energy polarization channels, providing an indication if
there are hidden explosives or weapons in the object based on said
parameters.

[0033] In accordance with certain embodiments, there is provided a method
wherein the transmitter being a radar system configured to transmit a
Frequency Modulated Continuous Wave (FMCW) or pulsed or CW signal.

[0034] In accordance with an aspect of the invention, there is provided a
system for detecting hidden explosives or weapons, comprising a [0035]
a polarimetric transmitter/receiver module which is configured to switch
between horizontal and vertical polarized signal transmissions utilizing
a transmitter antenna; [0036] a receiver configured to receive a back
scattered signal and split the received signal into vertical (V) and
horizontal (H) components; [0037] A2D configured to receive said vertical
(V) and horizontal (H) components through V and H channels and converting
the backscattered signals into digital signals; [0038] a processor
configured to process the digitized signals for determining whether the
object conceals explosives or weapons.

[0039] In accordance with certain embodiments, there is provided a method
wherein said module being a Frequency Modulated Continuous Wave (FMCW) or
pulsed or CW module.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to understand the invention and to see how it may be
carried out in practice, a preferred embodiment will now be described, by
way of non-limiting example only, with reference to the accompanying
drawings, in which:

[0041]FIG. 1 illustrates a general schematic layout of a system in
accordance with certain embodiments of the invention;

[0042]FIG. 2 illustrates a general system architecture, in accordance
with certain embodiments of the invention;

[0043]FIG. 3 illustrates a generalized sequence of operation of a system
in accordance with certain embodiments of the invention;

[0044]FIG. 4 is a graph representation illustrating utilization of
threshold for identifying an armed human; and

[0046] Turning now to FIG. 1, there is shown a general schematic layout of
a system in accordance with certain embodiments of the invention. As
shown a video camera fitted on system 12 (powered through power supply 17
) that incorporates a transmitter/receiver radar system configured to
transmit a Frequency Modulated Continuous Wave (FMCW) beam that covers
the entire or part of the object of interest (by this particular example
a suspected person 13 potentially carrying concealed explosives and/or
weapon). An imaging means (such as video camera 11 ) is aligned with the
operation radar system by means of positioning motor 14. System 12
communicates with computer 15 fitted with enhanced DSP capabilities for
performing the pertinent processing of the reflected signals that are
received by receiver of system 12, all as will be discussed in greater
detail below. The computer 16 may be used for example for video recording
of the scene and/or the resulting analysis (e.g. indication on whether
explosive substances have been revealed).

[0047] Note that in accordance with certain other embodiments a pulsed or
CW radar is used.

[0048] Bearing this in mind, attention is drawn to FIG. 2, illustrating
generalized system architecture in accordance with certain embodiments of
the invention. As shown, the system includes a power supply unit 21
coupled to polarimetric transmitter/receiver FMCW module 22 which is
configured to switch between horizontal and vertical polarized beam
transmissions (through Transmitter antenna 23 ) towards the object of
interest. The back scattered signal is received by receiver antenna 24,
split into vertical (V) and horizontal (H), processed in module 22 and
fed through two channels V (25) and H (26) to an A2D 28 and DSP 29 in
computer 27. The PC and the associated DSP module 29 (serving for
accelerating computation) are configured to process the digitized signal
for determining whether the object conceals explosives or weapons, all as
will be described in greater detail below. Also shown is a video camera
201 coupled to portable PC video monitor 202 for monitoring and perhaps
pointing at a specific target. The target may conceal explosives or
weapons. The video camera is aligned to antenna allowing receiving video
image of the object that is illuminated by the radar beam. In accordance
with certain embodiments the imaging means (such as the specified video
camera) are not only configured to monitor the object of interest but may
also serve to point at it (e.g. by a laser beam).

[0049] Since the transmitted signal is coherent, Doppler processing can
also be performed thus generating four range-Doppler maps (one for each
transmit-receive polarizations combination).

[0050] Note also that whereas the system of FIG. 2 illustrates a
stationary radar designated to track moving object (such as armed human)
or a stationary one (say explosives or weapons, hidden in, say bushes),
it likewise applies to a moving platform (say an airborne radar)
designated to track stationary or moving objects, mutatis mutandis. In
accordance with certain embodiments the explosives or weapons may include
hidden missiles or launchers concealed in say bushes.

[0051] Attention is now drawn to FIG. 3, illustrating a sequence of
operations of signal processing steps, in accordance with certain
embodiments of the invention. Thus,

[0052] At step 31, the procedure for detection of concealed weapons or
explosive commences. At stage 32, Range--Doppler maps are generated and
evaluated. At stage 33 the target is detected and tracked based on
energetic and dimensional features (sum of intensities in all
polarization channels). Then (34), full polarization scattering matrices
of RD (Range Doppler) cells belonging to the target are evaluated.

[0053] Next 35, correlations between elements of the polarization
scattering matrices are calculated, to obtain the covariance matrix, its
eigenvalues and eigenvectors, all as will be explained in greater details
below.

[0054] The specified steps 31 to 35 are repeated while tracking the target
and gathering its parameters as well as the results of the polarization
correlations for several maps (e.g. 50), giving rise to track length, say
in the latter example 50.

[0055] In the case that the track length exceeds 50, then in step 37, the
eigenvalues' and eigenvectors' statistics are evaluated (in a manner that
will be discussed in greater detail below). Based on the analysis, a
decision is taken and indication is provided 38 whether a concealed
explosive or weapon has been detected and if in the affirmative,
appropriate measures (such as alarm) are activated 39.

[0056] In accordance with certain embodiments the detection of the
concealed explosives/weapons can be synchronized with the imaging means
which can either monitor the target object or point thereto in the case
of detection.

[0057] For a better understanding of the computational steps described
with reference to FIG. 3, attention is drawn to the following discussion:

[0058] Thus, in step 34, once a target is detected the scattering matrix S
defined by equation 1:

[0060] The received back scattered digitized signals compose a 2×2
back scattering matrix with the following elements:

[0061] Shv standing for backscattered signal in the vertical channel
(25 of FIG. 2) originated from transmitted horizontally polarized signal.
Note that in armed human this value is relatively high compared to non
armed human. The underlying rational is that unlike the human body which
tends to scatter the impinging radar beam in the same direction (i.e.
impinging horizontally polarized beam will be substantially
back-scattered in the horizontal direction), the concealed
explosives/weapons tend to scatter the impinging beam also in other
directions. Thus, for example a horizontally polarized beam will be
scattered also in the vertical direction.

[0065] Multiplying the transmission vector by the backscattering matrix
results in the "received vector" composed of the Eh and Ev
elements of equation 1.

[0066] In accordance with step 35, since the correlation between elements
of the scattering matrix S over groups of Range Doppler cells are of
interest, it is convenient to switch to a vector notation as follows
(equation 2):

Z = [ S hh S vh S hv S vv ] ( 2 )
##EQU00002##

[0067] Further in accordance with step 35, the covariance matrix is then
given by equation (3), as follows:

[0068] Note that each element in the the 4×4 covariance matrix
includes two members selected from the group of Shh, Shv,
Svh and Svv as discussed with reference to equation 1 above.
Note also that "*" denotes the complex conjugate of the complex number
and < > denotes average over all relevant cells. Thus, assuming
that a given horizontally polarized beam impinges on a human target, it
is likely that back scattered signals will be reflected from few
locations of the human body. These multiply reflected signals are
averaged and the average values <|Shh|2>, <Shh,
Svh*>, <Shh, Shv*>, <Shh, Svv*>,
<Svh, Shh*>, <|Svh|2>, <Svh,
Shv*>, <Svh, Svv*>, <Svh, Svd*>,
<|Shv|2>, <Shv, Svv* >, <Svv,
Shh*>, <Svv, Svh*>, <Svv, Shv*>,
and <|Svv|2> are used in the correlation matrix.

[0069] Still in accordance with step 35, in order to analyze the
properties of the covariance matrix C, the eigenvalues and its
eigenvectors are calculated. As is well known, the sum of the eigenvalues
is tr(C) (i.e. the total energy reflected from the target). The
corresponding eigenvector gives the relative components of the four
different combinations of transmit-receive (TR) polarization.

[0070] In accordance with certain embodiments, the eigenvalues are
normalized (by dividing the matrix C by its trace to obtain tr(C)=1). The
eigenvectors V are also normalized such that |V|=1. Note that the matrix
C has four eigenvalues and corresponding four eigenvectors (one for each
eigenvalue). In accordance with certain embodiments only the largest
eigenvalue and its corresponding eigenvector values are considered. The
invention is of course not bound by considering the
eigenvalues/eigenvectors in the manner specified and not by the usage of
the largest values thereof.

[0071] In accordance with certain embodiments all the information about
polarimetric correlations is contained in the eigenvalues and
eigenvectors of the matrix C. The description below elaborates, in
accordance with certain embodiments, how to map different materials in
the eigenvalue-eigenvector space.

[0072] Note that the invention is not bound by the specified notations.
Note also that the implementation of steps 34 and 35 is not bound by the
specified sequence of calculations.

[0073] The utilization of the eigenvalues and eigenvectors (as discussed
by way of example above), for determining whether the object conceals
weapons and/or arms (step 37 and 38) will be better understood with
reference to FIGS. 4 and 5, below).

[0074] Turning first to FIG. 4, it illustrates graphs depicting a
threshold serving for identification whether the object is armed or
unarmed. The ordinate denotes the normalized eigenvalues whereas the
abscissa denotes cumulative population percentage. As explained above,
the normalized eigenvalue for an unarmed person is theoretically 1.
However in real-life scenarios it is likely that certain deviations will
be encountered. Accordingly, consider X (say 50) consecutive measurements
(i.e. target detections). In each measurement horizontally and vertically
polarized radar signals are transmitted towards the object, and the
backscattered are separated into vertical and horizontal polarization
components, and are then digitized and processed to obtain RD map and
detect the targets. For each target the appropriate covariance matrix and
its eigenvalues and eigenvectors are calculated in the manner discussed
in detail above, and their values are recorded. Theoretically, for an
unarmed person, a 100 % of the population (i.e. all X measurements)
should give an eigenvalue of nearly 1. This is denoted by the (x, y)
value 41 on the cumulative distribution function of an unarmed person in
FIG. 4. However in certain measurements say 5 measurements (i.e. 10% of
the total 50 measurements) the eigenvalue is less than 0.95. This is
denoted by the (x, y) value 42 and is within the expected statistical
error.

[0075] Turning now to the dashed graph in FIG. 4 representing the
eigenvalue cumulative distribution function of an armed object where, as
discussed in detail above, a significant backscattering exists in the
cross-polarized channel (i.e. transmitting a horizontally polarized
signal yields significant vertically polarized backscattering and vise
versa). Consequently, the resulting eigenvalue is in many cases (say for
instance in 25% of the measurements namely in 13 out of the 50
measurements) less than 0.86 and for 10% less than 0.76. The latter
points are depicted as (x, y) values 43 and 44 in FIG. 4 on the graph
representing an armed person.

[0076] Note that the description with reference to FIG. 4 focused mainly
on eigenvalues is more for illustrative purposes whereas more accurate
results are achieved by analyzing not only the eigenvalues but also the
eigenvectors.

[0077] Turning now to FIG. 5, it shows a graph representation illustrating
utilization of threshold for identifying an armed person. The data
plotted are eigenvalues in the ordinate vs. eigenvectors in the abscissa.
Line 51 separates the measurements such that points below the line (e.g.
53) indicate an armed person whereas points above it (e.g. 52) indicate
an arm-free person.

[0078] Considering for example 50 measurements, each point depicted in
FIG. 5 is at eigenvalue (ordinate) such that 10% of the targets'
eigenvalues evaluated in these measurements are below it and at
eigenvector (abscissa) such that 10% of the targets' eigenvectors
evaluated in these measurements are below it. Thus considering (x, y)
value 52, the ordinate value 0.89 denotes that 10% of the measurements
(i.e. 5 out of 50) had eigenvalues that dropped below 0.89. The abscissa
value of 0.54 indicates that 10% of the measurements (i.e. 5 out of 50)
had eigenvectors that dropped below 0.54. Since the coordinates of 52 (
0.54, 0.89) are such that this point is above the separating line 51, it
belongs to an unarmed person (as was indeed the case). Turning now to the
point 53 of FIG. 5, this point is at eigenvalue 0.82 and at eigenvector
0.43, namely, in 10% of the tested targets the eigenvalue was below 0.82
and similarly 10% of the tested targets had eigenvectors smaller than
0.43. Considering that the point 53 (0.43, 0.82 is below line 51, it
belongs to an armed person (in agreement with the experimental setup).

[0079] In accordance with certain embodiments, it is sufficient to analyze
one value of 50 measurements (e.g. 52 or 53 discussed above). In
accordance with certain other embodiments a certain criterion may be
applied to plurality of such points before conclusion is made, e.g.
requiring that a cluster of few points that reside below line 51 in order
to indicate a detection of an armed person.

[0080] This is denoted by the (x,y) value 52 indicating that 10% of the
population has a normalized eigenvalue less than 0.9

[0081] In the case of detection appropriate means can be invoked such as
alarm, orienting imaging means such as video camera towards the detected
object, various kill means and/or others which the case may be.

[0082] Note that the numerical value in FIGS. 4 and 5 are provided for
illustrative purposes only and do not necessarily reflect real life
values.

[0083] Note that the invention is not bound by the specific utilization of
eigenvalues and eigenvectors for determining armed or unarmed person, as
described with reference to FIG. 5.

[0084] Assuming by way of non limiting example, that every measurement
(including processing) takes about 60 msec then within 50 measurements
(i.e. 3 seconds) an alarm can be activated in the case that an armed
human has been detected. Note that in accordance with certain embodiments
multiple targets can be tracked.

[0085] Unless specifically stated otherwise, as apparent from the
following discussions, it is appreciated that throughout the
specification discussions, utilizing terms such as, "processing",
"computing", "calculating", "determining", "evaluating", "analyzing" or
the like, refer to the action and/or processes of a computer or computing
system, or processor or similar electronic computing device, that
manipulate and/or transform data represented as physical, such as
electronic, quantities within the computing system's registers and/or
memories into other data, similarly represented as physical quantities
within the computing system's memories, registers or other such
information storage, transmission or display devices.

[0086] Embodiments of the present invention may use terms such as,
processor, computer, apparatus, system, sub-system, module, unit, device
(in single or plural form) for performing the operations herein. This may
be specially constructed for the desired purposes, or it may comprise a
general purpose computer selectively activated or reconfigured by a
computer program stored in the computer. Such a computer program may be
stored in a computer readable storage medium, such as, but not limited
to, any type of disk including optical disks, CD-ROMs, magnetic-optical
disks, read-only memories (ROMs), random access memories (RAMs),
electrically programmable read-only memories (EPROMs), electrically
erasable and programmable read only memories (EEPROMs), magnetic or
optical cards, any other type of media suitable for storing electronic
instructions that are capable of being conveyed via a computer system
bus.

[0087] The processes/devices (or counterpart terms specified above) and
displays presented herein are not inherently related to any particular
computer or other apparatus, unless specifically stated otherwise.
Various general purpose systems may be used with programs in accordance
with the teachings herein, or it may prove convenient to construct a more
specialized apparatus to perform the desired method. The desired
structure for a variety of these systems will appear from the description
below. In addition, embodiments of the present invention are not
described with reference to any particular programming language. It will
be appreciated that a variety of programming languages may be used to
implement the teachings of the inventions as described herein. As used
herein, the phrase "for example," "such as" and variants thereof
describing exemplary implementations of the present invention are
exemplary in nature and not limiting. Reference in the specification to
"one embodiment", "an embodiment", "some embodiments", "another
embodiment", "other embodiments" or variations thereof means that a
particular feature, structure or characteristic described in connection
with the embodiment(s) is included in at least one embodiment of the
invention. Thus the appearance of the phrase "one embodiment", "an
embodiment", "some embodiments", "another embodiment", "other
embodiments" or variations thereof do not necessarily refer to the same
embodiment(s). It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate embodiments,
may also be provided in combination in a single embodiment. Conversely,
various features of the invention, which are, for brevity, described in
the context of a single embodiment, may also be provided separately or in
any suitable subcombination. While the invention has been shown and
described with respect to particular embodiments, it is not thus limited.
Numerous modifications, changes and improvements within the scope of the
invention will now occur to the reader.

[0088] It will also be understood that the system according to the
invention may be a suitably programmed computer. Likewise, the invention
contemplates a computer program being readable by a computer for
executing the method of the invention. The invention further contemplates
a machine-readable memory tangibly embodying a program of instructions
executable by the machine for executing the method of the invention.

[0089] While certain features of the invention have been illustrated and
described herein, many modifications, substitutions, changes, and
equivalents will occur to those skilled in the art. It is therefore to be
understood that the appended claims are intended to cover all such
modifications and changes as fall within the scope of the claims.

Patent applications by Igal Greenberg, Hod Hasharon IL

Patent applications by ISRAEL AEROSPACE INDUSTRIES LTD.

Patent applications in class TRANSMISSION THROUGH MEDIA OTHER THAN AIR OR FREE SPACE

Patent applications in all subclasses TRANSMISSION THROUGH MEDIA OTHER THAN AIR OR FREE SPACE